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Push rod through rocker

I was a BB Chev fan for many years before switching to Mopar (I wanted to go faster). I think you stand a better chance of winning the lottery then finding BB Chev push rods working well in your 413 Mopar. The lenght of the BB chev push rods is different between intake and exhaust, if I remember correctly the intake push rods are shorter than the exhaust, so what did your builder use all intakes or all exhaust? If they are mixed that would be most of the problem. Building a couple of 440s by now I have learned the push rod length is more important after a cam change on the 440 than it is on a 454. The stud mounted rocker has more adjustment to it than the shaft mounted rocker of the Mopar engine. Mike67 and Ski 61701 are right the push rod length is the problem.
 
Was thinking the same thing. I know very little about GM engines but why would anyone use Chevy pushrods in a Mopar. Your machinist might be really good with GM products but just how good is he with Mopars? In all the years of being into Mopars, this is the first time I ever heard of anyone using big block Chevy push rods in a Mopar. One more thing...are the rockers factory stock or are they the MP performance heavy duty ones? There is a difference. A buddy and I put a 318 together using a .480 lift cam using the MP rockers, springs to match and turn that thing 6200 without any problems. Yeah, it's a small block but they used the same rocker set up and oil them the same as the big blocks....
 
Just received Kar Krap mag Feb 17 issue has an article on BB Mopar roller rocker. They screwed up a set of pushrods.
 
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Did some measuring and looks like lifter cup is pushed down 39 thousand with valve fully opened and 24 thousand with valve closed, not sure how bad that is but thinking pushrods are to long and will talk to engine builder on Monday
 
Wonder if the lifters pump up at 5000 rpm and add .039 to the lift? I haven't used hyd lifters so maybe somebody else can answer?
 
hashmaker said:
I was a BB Chev fan for many years before switching to Mopar (I wanted to go faster). I think you stand a better chance of winning the lottery then finding BB Chev push rods working well in your 413 Mopar. The lenght of the BB chev push rods is different between intake and exhaust, if I remember correctly the intake push rods are shorter than the exhaust, so what did your builder use all intakes or all exhaust? If they are mixed that would be most of the problem. Building a couple of 440s by now I have learned the push rod length is more important after a cam change on the 440 than it is on a 454. The stud mounted rocker has more adjustment to it than the shaft mounted rocker of the Mopar engine. Mike67 and Ski 61701 are right the push rod length is the problem.
Click to expand...

Nothin' says lovin' like a push rod length checker and a custom length set of rods from Trend Performance. You'll also need to remove one set of valve springs (intake and exhaust) and using a checking spring determine valve to piston clearance. Compressed air and good feeler gauges will be required to check this distance.
 
8.9 to 1 compression, so don't think valve clearance is an issue but could be wrong. Would of thought the engine builder would of checked push rod length since I asked him to. And he is a reputable builder.
 
Cranky said:
Was thinking the same thing. I know very little about GM engines but why would anyone use Chevy pushrods in a Mopar. Your machinist might be really good with GM products but just how good is he with Mopars? In all the years of being into Mopars, this is the first time I ever heard of anyone using big block Chevy push rods in a Mopar. One more thing...are the rockers factory stock or are they the MP performance heavy duty ones? There is a difference. A buddy and I put a 318 together using a .480 lift cam using the MP rockers, springs to match and turn that thing 6200 without any problems. Yeah, it's a small block but they used the same rocker set up and oil them the same as the big blocks....
Click to expand...
Stock after market, not sure of brand
 
Fran Blacker said:
Wonder if the lifters pump up at 5000 rpm and add .039 to the lift? I haven't used hyd lifters so maybe somebody else can answer?
Click to expand...
Ideal preload for normal application is .020"-.040". The correct ball pushrods and the stock rockers will work. I've had them break on new builds. Usually a few brake and then it stops. Picks on the weak link. You have proper preload so the push rod length is as good as it gets with a non-adjustable valve train.
Doug
 
dvw said:
Ideal preload for normal application is .020"-.040". The correct ball pushrods and the stock rockers will work. I've had them break on new builds. Usually a few brake and then it stops. Picks on the weak link. You have proper preload so the push rod length is as good as it gets with a non-adjustable valve train.
Doug
Click to expand...
What made me think about lifters pumping up, a friend of mine worked a dealership in 1968 thru 70. The early Six Pack cars were popping hyd. lifters apart. After a few came back for warranty work somebody discovered that the oil pumps were putting out over 100 lbs pressure. They changed the pressure relief springs in the oil pumps.
 
Just thinking out loud, again. Interesting about those six-pac lifters. And, someone said oil pressure has no affect on lifters.
Curious, with all those beat up parts, how's the cam lobes look?
Guess the way tappets are made these days, have to pay attention. Pump-up, and bleed-down rates a big affect, along with the preload.

I've come across my share of bent push rods in motors I've busted down...but, nothing like you have.
 
Someplace in this rocker system there is and interference fit and it must be corrected. There is nothing wrong with running an oil-through pushrod. And unless the builder has used the AMC style lifters there won't even be any oil passing through the pushrod. Often oil-through pushrods are used in high spring pressure application to get a little more oil to the pushrod/adjuster junction. Sometimes I use the hollow pushrods because they are stocked in a plethora of different sizes and easier to get quickly. Never had a failure with them.
 
IQ52 said:
Someplace in this rocker system there is and interference fit and it must be corrected. There is nothing wrong with running an oil-through pushrod. And unless the builder has used the AMC style lifters there won't even be any oil passing through the pushrod. Often oil-through pushrods are used in high spring pressure application to get a little more oil to the pushrod/adjuster junction. Sometimes I use the hollow pushrods because they are stocked in a plethora of different sizes and easier to get quickly. Never had a failure with them.
Click to expand...
I don't see a problem with using oil through PR's either....but is the size of the ball the same on a Chevy PR?
 
miller said:
Just thinking out loud, again. Interesting about those six-pac lifters. And, someone said oil pressure has no affect on lifters.
Curious, with all those beat up parts, how's the cam lobes look?
Guess the way tappets are made these days, have to pay attention. Pump-up, and bleed-down rates a big affect, along with the preload.

I've come across my share of bent push rods in motors I've busted down...but, nothing like you have.
Click to expand...
I looked at the cam both times and it still look OK, so I hope it will still work, still wondering doing roller rockers for strength, just don't like this happening.
 
May of found the problem, in the picture the rocker on the bottom is the replacement the engine builder gave me after the first pushrod went through the rocker, hard to tell in picture but notice the ball socket on the bottom vs the one on the top, ball hole on bottom Is bigger and fits pushrod ball better, is there a difference in small and big block rockers

2016-11-27 16.29.18.jpg
 
Yes that appears to be a problem. How does the pushrod fit in each one. I could see if it fits tight in the upper one there could be some binding going on an viola popped rocker arm. There is a difference between small and bigblock rockers. But I am not 100% sure what it is whether its overall length or if it has to do with the diameter of the cup on the arm itself. I think you are on the right track.
 
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